IEEE 29148:2011 States a ConOps is a user oriented doc that describes the system characteristics from a users perspective.
From a CBTC perspective, a ConOps is written with the end-user in mind and it describes what the transit agency expects from the CBTC system.
The ConOps is concerned with the operating environment (blue area) where the CBTC system will reside in and where frontline personnel work to deliver service.
The CBTC system must address the needs of these frontline personnel and the purpose of the ConOps is to capture the needs of these workers.